by Jabeen Bhatti, A. Khelifa and Josie Le Blond, Special for USA TODAY

by Jabeen Bhatti, A. Khelifa and Josie Le Blond, Special for USA TODAY

TUNIS, Tunisia - The Tunisian Islamist-led government was dissolved late Wednesday after thousands took to the streets in outrage over the assassination of one of the government's fiercest critics, throwing the country's post-revolution transition into turmoil.

Tunisian Prime Minister Hamadi Jabali said he was replacing the government with technocrats unaffiliated with the ruling Islamists or its secular coalition partners after the murder of opposition leader Chokri Belaid, who was gunned down in front of his Tunis home Wednesday morning.

"(The murder) was a heinous crime against the Tunisian people," he said. "The murder of Belaid is the assassination of the Tunisian revolution."

Earlier Wednesday, the country saw the largest protests since the revolution two years ago, as thousands of Tunisians took to the streets, expressing outrage over the killing and fears that the country's democratic transition is being derailed.

Police fired tear gas at thousands of demonstrators across the country in scenes reminiscent of the weeks of protests that ousted dictator Zine El Abidine Ben Ali in January 2011 - the first of the Arab Spring uprisings.

Some Tunisians said they were shocked that what has been a mostly peaceful revolution and transition to elected government has turned this violent.

"They have killed a loud voice which always defended the oppressed," said Ridha Chakroun, a political activist who was visibly distraught. "The questions we need to ask now are who ordered this assassination?"

Leader of the Democratic Patriotic Party, Belaid, 48, was also head of the umbrella opposition group, the Popular Front, and a leading critic of the ruling Islamist party, Ennahda.

Over the weekend, Belaid accused Salafists - hard-liners who want an Islamic theocracy in Tunisia - of threatening opposition members. Salafists have targeted for destruction mausoleums, art exhibitions and TV stations they deem violate their strict interpretation of Islam.

"There is a small but potent Salafi Jihadi militant segment in Tunisia that has become very dangerous," said Fawaz Gerges, director of the Middle East Center at the London School of Economics. "The killing of Chokri sends a message loud and clear that they will try to silence secular voices, and they will accept no criticism even of the Islamist-based Ennahda government."

The revolution two years ago opened up Tunisia's political system to a multitude of parties, including the long-persecuted Muslim Brotherhood. It also freed extremists that for years had been forced underground in one of the most secular societies in the Arab world.

Now some worry that Ennahda, which came to power after Tunisia's first democratic elections in October 2011, is not doing enough to rein in the extremists.

"Ennahda is in power - they have a huge moral and legal responsibility to prevent extremist elements from undermining social peace and harmony," Gerges said.

Tunisian President Moncef Marzouki described Belaid as a friend and denounced the assassination. He said Tunisia would fight "the enemies of the revolution."

Tunisia erupted in demonstrations In December 2010 after a fruit and vegetable vendor set himself on fire to protest dictatorial rule. That led to the Arab Spring uprisings that spread to Egypt, Libya, Yemen and Syria.

Tunisia has avoided the extreme violence of its neighbors in the region but it has experienced clashes between the Islamists and moderates as well as strikes and demonstrations over the state of its ailing economy and high unemployment.

In recent weeks, the Islamists have been negotiating with their coalition partners, secular opposition parties, for a cabinet reshuffle to make the government more inclusive.

Belaid had regularly received death threats because he had been particularly critical of the Committees to Protect the Revolution - which are blamed for much of the violence. These groups, associated with the Islamists, say they want to cleanse the government of the old guard.

Some complain that Ennahda should have done more to stem the threat posed by the extremists.

"There have been signs predicting the escalation of violence but nobody took them seriously - taking action against those who openly preached violence," said Nabil Cherni, a lecturer at Manouba University in Tunis. "This is the first political assassination in post-independence Tunisia - we might be entering a new phase now."